sometimes a design has to jiggled around to add additional blocks or parts, but it can be done. if necessary, i'll go to 100", but i don't like to because it's tight on my frame. if i have too much trouble with a particular pattern, then i just toss it out.
there are enough terrific ones not to have to spend a week doing the math that will get me the results i want.
some things are not meant to be.